Possible encounter while bow hunting for elk near Florence witnessed in Lane County, Oregon

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My partner and I were bow hunting for elk just outside of the major power lines running down the North Fork of the Siuslaw River. He set up to call elk under the power lines just in the brush from the open field area and I proceeded up the road as it enters the forest to set up at a creek area the road crossed. As I approached my set up point, I could clearly hear a very loud knocking. It was not patterned but was like a sound I have never heard in my 30 years of hunting in Oregon forests. It sounded very distinctly of stone, possibly an enormous piece of wood but I really have decided it had to be stone, on a very hard substance of some sort, like a solid piece of wood. This knocking had to be less than 75 yards from where I was. It would continue in small groups, like 3 to 4 knocks, pause, then follow up between 10 and 20 seconds with 1 or 2 more knocks, silence for around a minute and go again. This went on long enough that I was seriously starting to think a person might be u...